Demo

Direction

1. File > New > any size (mine used 250x250 pixels) with white background.

2. Press D.

3. Select Gradient Tool and choose option to Linear Gradient ().

4. Draw a line from the top to the bottom of your document.

5. Go to Filter > Distort > Wave, use these settings.

6. Go to Filter > Distort > Polar Coordinates, use default settings.

7. Press Ctrl + I.

8. Press Ctrl + U > check Colorize, use these settings or other that you like.

9. Duplicate layer and set its mode to Color Dodge.

10. You are done.